I'll finally jump into this discussion, which only seems fair since it was
my usage of "rostral" that got this whole thing started. Also, as an
official "nomenclator," I've thought about it a fair amount.
This issue about the cranial/caudal convention comes up surprisingly often,
despite being of so little scientific significance. For those who have
been wondering what this thread has been all about, here's a brief synopsis.
In anatomical terminology, there are terms of orientation that tell us
about relative position in a body. For humans: anterior means toward the
front, posterior means toward the back, superior means toward the top of
your head, inferior means toward the bottoms of your feet. The problem has
been that humans are weird, as animals go, because of our upright posture.
Veterinarians were the first group to complain because the terms didn't
work well for quadrupeds. For example, all the terms relating to vertebrae
are 90 degrees different: the centrum (body of the vertebra) is anterior in
humans but "inferior" in, say, a dog.
An international organization of veterinary anatomists, got together about
a hundred years ago to try and stabilize the multitudinous anatomical terms
that had been floating around. They also tried to deal with the terms of
orientation. Eventually this organization (now known as the World
Association of Veterinary Anatomists) decided to abandon the anterior/
posterior/superior/inferior convention of human anatomy and proposed a new
one:
cranial: toward the head or front end
caudal: toward the tail or back end
ventral: toward the belly
dorsal: toward the back
lateral & medial retain their familiar meanings
The head and tail present certain problems, so within the head:
rostral: toward the tip of the nose
Within the tail:
proximal: toward the base of the tail
distal: toward the tip of the tail.
(Thus, George Olshevsky goofed a bit: we talk about proximal caudal
vertebrae, not cranial caudal vertebrae).
On with the history, these terms of orientation were picked up by
veterinary anatomists worldwide and have been codified in the official
guide, Nomina Anatatomica Veterinaria. Incidentally, these are also the
terms of orientation for human embryology.
More recently, the International Committee on Avian Anatomical Nomenclature
(of which I am Chair of the Osteology Subcommittee) adopted the cranial/
caudal convention for birds, which has been published in Nomina Anatomica
Avium.
Most recently, the editors of _The Dinosauria_ adopted the cranial/caudal
convention for their book. Thus, George made a rare historical lapsis
here. _The Dinosauria_ wasn't trying to ramrod anything through. The
editors were simply trying to get on-board and in line with the rest of non
-human anatomical nomenclature. For what it's worth Luis Chiappe and I
will be using the convention in the book we're editing on Mesozoic birds.
Now, here's the important point: this is a convention, and nothing more.
We can debate whether cranial/caudal is better or worse than anterior/
posterior. But what's the point? Dinosaur paleontology is one relatively
small segment of the anatomical community---a community that almost
universally has accepted the cranial/caudal convention. I can promise
that nobody on any of these official nomenclatural committees cringes or
loses sleep about people saying "anterior." We have sucked it up and said,
that's the convention, we're on board, let's talk about something
interesting. These debates are about names, not things. Things are more
important---and more interesting. Nomenclature is important for
communication, but it's an end to communicating about _things_ not about
names. Let's talk about things. -- Larry Witmer
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(until 12 Aug 95)
Lawrence M. Witmer, PhD | (after 1 Sept 95)
Assistant Professor of Anatomy | Dept of Biological Sciences and
Department of Anatomy | College of Osteopathic Medicine
NY College of Osteopathic Medicine | Ohio University
Old Westbury, NY 11568 USA | Athen, Ohio 45701 USA
e-mail: lwitmer@acl.nyit.edu | e-mail:witmer@mail.oucom.ohiou.edu
phone: (516) 626-6944 ext. 6808 |
fax: (516) 626-6936 |
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